EXO BARRIER - Protective coating bonds to exterior lenses repelling water oil dust and debris for clear viewing in even the worst weather. ED PRIME GLASS - Delivers best-in-class color even in low-light situations FULLY MULTI-COATED OPTICS - Applied to the prisms it enhances resolution and contrast for brightest possible images. ENVIRONMENTALLY FRIENDLY - Lead Free Glass WATERPROOF CONSTRUCTION - Resists rain fog and accidentalsubmersion for clear viewing in any weather NITROGEN PURGED FOD-PROOFING